Catalytic metalloporphyrin chemistry will be utilized to develop a chemical treatment process for silicone membrane surfaces. Specifically, this process (a) will selectively hydroxylate methyl groups on dimethylsiloxane oligomers and polymers at ambient temperature (b) will minimize additional surface crosslinking and contamination, common side effects and byproducts observed in plasma etching of silicones in oxygen-containing atmospheres; (c) will produce surfaces that can be further developed for covalent attachment of anti-thrombogenic compounds. The proposed Phase I R&D project will: (a) evaluate the efficacy, selectivity, and specificity of metalloporphyrin-catalyzed oxidations of silicone materials; (b) identify effective reagents and optimum conditions for surface chemical treatments and determine the nature and distribution of hydroxylated surface sites; and (3) evaluate the efficiency of the chemical treatment process on surfaces coated by dipping and plasma polymerization techniques.